X0508 4 2025-03-21 0000354190 Arthur J. Gallagher & Co. AJG 0001482241 Hudson Scott R 2850 GOLF ROAD ROLLING MEADOWS IL 60008-4002 1 Vice President 0 Common Stock 2025-03-21 4 G 0 300 0 D 97530 D Common Stock 2025-03-21 4 S 0 7510 333.59 D 90020 D Common Stock 339.027 I Gallagher 401(k) plan account The price reported is an average weighted price. The shares were sold in multiple transactions at prices ranging from $333.38 to $333.89. The reporting person will provide to the Securities and Exchange Commission staff, the issuer, or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. /s/ Ryan Session, by power of attorney 2025-03-21